A turbocharger can extract energy from exhaust of an internal combustion engine using a turbine wheel. During operation, conditions may vary over time that can impact performance of the turbocharger. For example, a turbine wheel designed for high-energy (e.g., high flow) conditions may operate with less efficiency for low-energy (e.g., low flow) conditions. Various technologies, techniques, etc., described herein relate to turbine assemblies that may enhance efficiency for low-energy (e.g., low flow) conditions.